[揽瓜阁精读] 163. 河流是怎么形成的

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筱雅Jane510

163. 河流是怎么形成的
[Main Idea]
Present the scientists' hypothesis and researches about plants affected the rivers' form.

[Structure]
HYPOTHESIS
P1: MG's hypothesis -- land plants formed the modern rivers.
        P2: Plant roots reinforced the ground, and that is the basis for many Earth history events.

RESEARCH
P3: MG&ND compared plant fossil record to prove the hypothesis.
P4: They published the findings -- plants changed the landscape.
        P5: 500m years ago -- rivers were very shalow but wide.
                P6: That time and before the river was not formed by plants.
        P7: 420m years ago -- unconsolidated sedimentary rock appear less frequently.
        P8: River became more complex and diverse.
        P9: There was more lateral accretion.
        P10: The river's variation was related to the climate.

P11: 30 years ago, EC found that rivers changed a lot during 450m-250m years ago, by observing sedimentary rocks.
        P12: MG&ND researched later than EC, and had better conditions.
        P13: MG&ND reviewed 144 reports, visited 34 spots, and scrutinized experimental results.
        P14: Explain AF Lab's experiment.
        P15: AF Lab's result proved that plant roots could change river's pattern.

EVALUATION
P16: DC's evaluation about MG&ND's finding -- evidence of biotic & abiotic features's mutual influences.
        P17: -- deepen people's undersdanding of physical and biological processes on Earth.

FUTURE STUDY
P18: DC -- Whether the periodic extinction would affected the shapes of the rivers.
        P19: -- Whether river's form reverted.

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